This was another Friday night of meetings for the Giants, seemingly more of the same in the grind of training camp, when players last week were abruptly told to go somewhere other than where they were accustomed to going.

“Out of nowhere they were like ‘Just meet with the offensive coaches’ and we just went there,’’ cornerback Eli Apple said.

Why in the world would Apple and his fellow defensive backs have any business to be meeting with the Giants’ offensive coaches?

Well, consider this another one of Ben McAdoo’s unique and creative diversions, intent on serving a twofold purpose:

Provide fresh, new information while breaking up the monotony in a way that caters to the millennial generation that the 40-year-old head coach is consumed with reaching.

“It was 15 minutes and it was great,’’ Eli Manning told The Post.

Here is what went down. McAdoo instructed the quarterbacks, receivers and tight ends to head into the defensive backs’ meeting room, where cornerbacks coach Tim Walton and safeties coach Dave Merritt were stationed. The offensive linemen went into the defensive line room, where defensive line coach Patrick Graham was waiting. The defensive linemen were handed over to offensive line coach Mike Solari in the offensive line room. All the defensive backs sat down in the wide receivers’ meeting room for a tutorial from offensive coordinator Mike Sullivan, receivers coach Adam Henry, tight ends coach Kevin M. Gilbride and quarterbacks coach Frank Cignetti.

McAdoo calls it “cross-coaching’’ and he has not used it before, until now.

This falls in line with one of McAdoo’s favorite coaching mantras: Instilling “empathy’’ in his players.

“Having one side of the ball be able to understand what the other side of the ball is going through and what they’re being coached to do,’’ McAdoo told The Post after Wednesday’s practice.

This also checks the box marked “Teach innovatively.’’

“It also helps players get in a room and hear how the other side of the ball breaks them down fundamentally, the fundamentals that they’re being taught across the ball and then how they’re game-planning to beat the individual on the other side of the ball,’’ McAdoo said. “It helps to hear how opponents are going to try to coach and beat you as a man, it helps you work on your weaknesses.’’

Defensive tackle Jay Bromley, no doubt echoing the sentiments of a good portion of the team, was skeptical, initially.

“It was definitely more interesting than I thought at first,’’ Bromley said. “I was like, ‘Man, we’re just wasting time, we don’t need to learn O-line,’ but while we were in the room, coaches did a great job of explaining it and allowing us to understand what they go through.’’

Bromley’s greatest takeaway: How offensive linemen combat the long arms of opponents by making sure they cannot extend those arms.

Receiver Tavarres King appreciated hearing how defensive backs attempt to take away what the offensive player tries to accomplish.

“If they were shaded outside, what that meant; inside, what that meant,’’ King said. “It was basically like a small little DB tutoring session. It’s neat.’’

Manning said he was fascinated by the discussion on press coverage by cornerbacks.

“What they’re trying to do, what they’re looking for, when the receiver is making a release, their mindset on those things,’’ he said.

Of course, this session did not last long enough for the inquisitive quarterback.

“I could have asked a ton of questions and asked about different coverages, but it was very informative,’’ Manning said.

The defensive backs were told and shown what the quarterbacks are looking for on their drops and reads and how any slight disruption in timing could wreck the play.

“It gives you a different perspective of the offense and what they’re trying to accomplish,’’ Apple said. “The more you can know what the offense is thinking, it makes your job a little easier too.’’

McAdoo was thrilled with the results, saying, “We had to kick them out of the building. They really got into it.’’

The intangible benefits are sure to surface down the road.

Players and coaches who normally do not intermingle much were thrown together, creating more of McAdoo’s beloved empathy. The breaking of routine allowed the Giants to once again see that their head coach is embracing new ways.

“It was awesome. … Just another one of those things he does to put us in a different state of mind,’’ Apple said.

“You kind of get to go out of your room, go into somebody else’s room, in a new environment, that right there is gonna get your attention,’’ King said, “and then when they’re teaching you how to beat ‘em, that’s eye-opening as well. It was awesome. I’m glad Coach Mac did that. Just another one of those things he does to put us in a different state of mind.’’